Process and apparatus for recutting or sharpening all tools having numerous fine cutting edges



July 16, 1929. w, ROBE 1,721,414

PROCESS AND APPARATUS FOR REGUTTING OR SHARPENING ALL TOOLS HAVING NUMEROUS FINE CUTTING EDGES Filed Aug. 2, 192

Patented July 1%, l9.

WALTER B. ROBE, OF TQWSQN, MARYLAND, ASSIGNOR, T0 BEEN TOOL COMPANY, ING, OF BALTIMORE, MARYLAND, A COREORATIQN 0F MARYLAND.

PROCESS AND APIPARATUS FOR REQUESTING 0R SHAREENING ALL T OQLS ILAVING NUMEROUS FINE CUTTING- EDGES.

Application filed August 2, 1927. Serial No. 210,191.

My invention relates to improvements in process and apparatus for recutting or sharpening all tools having numerous fine cutting edges.

The object of my invention is to provide a process and apparatus more particularly designed for sharpening files, rasps and dental burrs in which the cutting edges are close together and whereb all of the fine cutting edges are evenly recut or sharpened by the combined action of an acid and an electric current, thus making the tools practically new.

Another object of my invention is to provide a process and apparatus of this char-' acter in which any number of tools can be simultaneously recut or sharpened, and in which the acid used in combination with the electric current will last about ten times as long as the acid when used. alone without the electric current, and in which every cutting edge is evenly sharpened.

.A further object of my invention is to provide a process and apparatus whereb tools of the character heretofore set fort may be more rapidly andcheaply sharpened, and at the same time making the entire tool like new.

In the accompanying drawings 1.-

Figure 1 is a vertical sectional view of a tank or container showing the apparatus by which the process is carried out.

Figure 2 is a top plan view of Figure 1,

, showing two bars 4; connected by a conduc tor.

Figure 3 is a perspective view of the tool supporting bar.

Tools of this character, heretofore set forth, have been sharpened by placing them or dipping them in acid, but such a process has been very objectionable in that the acid does not cut evenly, but causes the cutting edges to be rough or leaves a dirty coating on the surface of the tool, thus requiring a separate operation for cleaning the tool. The use of acid alone does not cut uniform-- ly but leaves high sharp points and pits in the cutting edges of the tool, and there has been no way of effectively sharpening this character of tool.

In carrying out my improved process, the apparatus comprises a tank or receptacle 1, made of either glass, wood or other material not efi'ected by the acid, and which as shownis nearly filled with acid. This acid comprises a mixture of copper sulphate, sulphuric acid, borax and acetic acid. The borax and acetic acid are used as neutralizers to prevent pitting. While I have described copper sulphate it will be under stood that silver sulphate or nitrate or any other basic metals in solution can be used.

Arranged in one end of the tank is the electrode 2 to which is connected one terminal 3 of the electric circuit. Arranged in the opposite end of the tank and supported thereby in any desired manner is a metal bar 4 having the other terminal 5 of the electr1c circuit connected thereto. This bar 5, for the purpose of illustration, is provided with a series of o enings 6 in which are arranged the tools by set screws 8, by means of which a good electric contact is formed between the bar 4; and the tool. The terminal 3 is the positive terminal, and the terminal 5 is negative. It has been found in actual practice that by passing a current of electricity from the electrode 2 to the tool 7 there is a deposit on the tool and by reversing the currenttor making the terminal?) negative and the bar 4 the positive, the metal is taken from the tool and partially deposited on the electrode or carried 01f by solution, which causes a cutting action or sharpening efi'ect on the fine cutting edges of the tool.

It has, however, been found that the most efiective process and apparatus of sharpening tools of this character is to employ an alternating current. When usin the alternatlng current the metal from t e electrode 2 israpidly carried across through the solution and deposited on the tool, then by the alternating current is rapidly removed from the tool and carried back rapidly to the electrode, causing a cutting or sharpening action.- It has been found that a low voltage is much more effective than a high voltage current, and will not cause any high points or its in the cutting edges of the tool but Wlll sharpen the tool and cause it to have the appearance of a new tool. The invention, as heretofore stated, 'is more cswhich are held therein pecially designed for dental burrs, files,

raspis, and any tool having a large number of fine cutting edges arranged so close to- V gether that it 'can not be sharpened in the usual manner of sharpening tools.

it has also been found that a pulsating urrent is very effective in carrying out my nvention.

'In Figure 2 I have slwvirn two bars 'conasing an electric current from through a solution of copper sulphate, sulphuric acid, borax and acetic acid to the tools.

2. The process of sharpening tools consistin in passing an alternating electric cur; rentom .an electrode through a solution of copper sulphate, sulphuric acid, borax and .acetic acid to the tools.

' 3. The process of sharpening tools consistprocess of sharpening tools con' ing in depositing and removingunetal from tools by an alternating ing'through a solution.

4. The process of sharpening tools consisting in depositing and removing metal from tools by an alternating electric current passing through a solution of copper sulphate.

he recess of sharpening tools consisting in epositing metal upon a tool by an electric current passin throu h a solution and removin the meta from t the e ectric current.

process of sharpening tools consiste tool by reversin 6.

ing in dpassing an electric current from-an electro through a solution of copper sulphate, borax and acetic acid to the tools.

\ In testimony whereof, I have signed this specification.

WALTEN B. ROBE.

electric current pass- 

